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Research Article
A taxonomic revision of Tragia (Euphorbiaceae) in Gabon, with a description of two threatened new species
expand article infoIris Montero-Muñoz‡§, Patricia Barberá|
‡ Real Jardín Botánico, CSIC, Madrid, Spain
§ Universidad de Alcalá, Madrid, Spain
| Universidad Autónoma de Madrid, Madrid, Spain
¶ Missouri Botanical Garden, St. Louis, United States of America

Corresponding author: Patricia Barberá ( patricia.barbera@uam.es )

Academic editor: João Farminhão
© 2025 Iris Montero-Muñoz, Patricia Barberá.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation: Montero-Muñoz I, Barberá P (2025) A taxonomic revision of Tragia (Euphorbiaceae) in Gabon, with a description of two threatened new species. Plant Ecology and Evolution 158(3): 367-381. https://doi.org/10.5091/plecevo.154149
Open Access

Abstract

Background and aims – The production of the Flora of Gabon is advancing biodiversity discovery and highlighting knowledge gaps in complex genera, such as Tragia. By studying this genus, we have identified new species to science and documented new country records for Gabon.

Material and methods – Standard practices of herbarium taxonomy were applied to study material from institutions with important holdings from Central Africa.

Key results – After a critical study of specimens from Gabon and surrounding territories, a total of six species of Tragia were identified in the country. Two new species, Tragia flagellata and T. sericea, are described and preliminarily assessed as Endangered (EN) and Vulnerable (VU), respectively. We cite Tragia mildbraediana and T. zenkeri as new records for Gabon. Comprehensive nomenclatural information is supplied and three lectotypes are designated. An updated identification key, an original illustration, photos of the new species, and maps are provided.

Keywords

Euphorbiaceae, Flore du Gabon, IUCN Red List, Plukenetieae, taxonomy, Tragia

Introduction

Gabon, situated on the Atlantic coast of Central Africa, has one of the richest floras in tropical Africa, with 85% of its area covered by evergreen forest (White 1979; Lachenaud et al. 2018). Due to the progress of taxonomic knowledge and the ongoing intensive botanical explorations in previously poorly known or unexplored areas in Gabon, many new species are described in the area every year, together with new additions to the country’s flora, and new records of little-known species (e.g. Couvreur and Niangadouma 2016; Lachenaud et al. 2017, 2018; Barberá et al. 2023; Quintanar et al. 2023; Cheek et al. 2024). A notable example of both the floristic richness of tropical Africa and the complexity of taxonomic delimitation is the genus Tragia L. (Euphorbiaceae, Acalyphoideae, Plukenetieae), in which new species are expected to be described from Gabon and surrounding countries.

Tragia includes ca 150 species widely distributed in tropical and warm-temperate regions worldwide, being the sixth largest genus in the family (after Euphorbia L., Croton L., Acalypha L., Macaranga Thouars, and Jatropha L.; Montero-Muñoz et al. in prep.). The highest diversity is present in Africa with more than 80 species, almost all endemic to the continent (POWO 2025; Montero-Muñoz et al. in prep.). Tragia is characterised by its abundant, urticating trichomes and the absence of stipels or laminar glands on the leaf blade bases (Radcliffe-Smith 2001; Webster 2014; Cardinal-McTeague and Gillespie 2016).

Floral and pollen morphology suggest that Tragia is polyphyletic (Gillespie 1994), which is confirmed by recent phylogenetic studies within the Plukenetieae tribe describing new genera (e.g. Chicomendes Sá-Cordeiro & M.F.Sales, Monadelpha L.J.Gillespie & Card.-McTeag.), and reinstating some segregates (e.g. Bia Klotzsch, Ctenomeria Harv., Zuckertia Baill.) (Webster 2007, 2014; Medeiros et al. 2013; Gillespie et al. 2020; Cordeiro et al 2021).

The last global revision of the genus dates back more than one century ago (Pax and Hoffmann 1919). After that, the African species of Tragia have not been revised as a whole, although a new revision is underway by the authors. Regionally, Tragia was revised for West and Central Africa by Prain (1913) and Keay (1958), with no new species being described since then. In East Africa and the Zambezian region, Tragia was revised by Radcliffe-Smith (1987, 1996), with a new species recently described from Malawi by Cahen et al. (2024). The genus has not yet been treated in the Flore du Gabon, Flore du Cameroun, or Flore d’Afrique centrale.

In Gabon, five species of Tragia were recorded in the national checklist of Sosef et al. (2006): T. benthamii Baker, T. laminularis Müll.Arg., T. preussii Pax, T. tenuifolia Benth., and T. volubilis L. However, when trying to identify recent collections from the country, we soon realised that most specimens cited were misidentified, and thus a revision of Gabonese Tragia was much needed. Barberá et al. (2013) already recognised the complexity of the group, provisionally identifying the group of unsatisfactorily delimited specimens from Equatorial Guinea as Tragia aff. tenuifolia. Here, we addressed this issue by confirming T. tenuifolia as endemic to São Tomé and Principe, describing T. flagellata sp. nov. and T. sericea sp. nov., and recording T. mildbraediana Pax & K.Hoffm. and T. zenkeri Pax for the first time in Gabon. Of the five species originally recorded in the country by Sosef et al. (2006), only T. benthamii and T. volubilis are confirmed as present, while records of T. laminularis, T. tenuifolia, and T. preussii are shown to be based on misidentifications (discussed below). These Gabonese species of Tragia seem to favour relatively open forest habitats where a significant amount of light penetrates the undergrowth. They are consequently mostly found along rivers, forest edges, in rocky areas (e.g. inselbergs), and in sclerophyllous littoral forests.

During the revision, we could locate only a limited number of Gabonese collections representing Tragia, indicating, possibly, that its species are generally uncommon in Gabon or undercollected. Furthermore, most collections were often misidentified or identified only to the genus. For example, some of the collections (Lejoly 96/23 and Sosef 921) previously cited in the checklist (Sosef et al. 2006) actually belong to Dalechampia Plum. ex L. All this makes Tragia a complex genus with still many gaps in its taxonomic and systematic knowledge.

Material and methods

This revision is based on a study of herbarium collections from BM, BR, BRLU, COI, G, IEC, K, LBV, LISC, LISU, MA, MO, P, and WAG (in L) (acronyms according to Thiers 2024), which include most of the collections from the country. Material from Cameroon, Equatorial Guinea, and Republic of the Congo has also been studied and cited. All examined specimens were seen in the herbarium or online (“image”) except those indicated as n.v. (non vidi). Additional type material was consulted online on JSTOR Global Plants (https://plants.jstor.org).

The descriptions of each species are based on the studied herbarium specimens, photographs, and field notes (including existing literature for the already described species); a genus description is included based on the species present in Gabon. Herbarium barcodes were included when available.

The accepted species are listed in alphabetical order. We provide type information for all accepted names. Lectotypes were designated according to the recommendations of the International Code of Nomenclature (Turland et al. 2018). Relevant nomenclatural or morphological information was included in the Notes section.

The morphological terms used in the descriptions are based on the definitions of Stearn (2004) and Beentje (2010). The information compiled on the habitat and ecology of each species was obtained from herbarium labels. For the distribution, we include a bibliographic reference when the species has already been reported for the country. Geographical coordinates were used to produce distribution maps, using QGIS Desktop v.3.28.4 (QGIS 2023) and Natural Earth (https://www.naturalearthdata.com/) layers. The maps represent the distribution of the species in Gabon and adjacent countries (Cameroon and Equatorial Guinea). When coordinates were not indicated on collection labels, specimens were georeferenced and such coordinates are presented between square brackets. We include preliminary conservation assessments of the two newly described species; they were performed following the IUCN Red List Categories and Criteria (IUCN Standards and Petitions Committee 2024). The geographical parameters of area of occupancy (AOO) and extent of occurrence (EOO) were calculated with GeoCAT (Bachman et al. 2011) using a 2 × 2 km grid.

Taxonomic treatment

Tragia Plum. ex L. (Linnaeus 1753: 980)

Lectotype species

Tragia volubilis L. (designated by Small 1913).

Description

Scrambling, scandent, or twining monoecious perennial, rarely annual, herbs or shrubs. Indumentum of simple hairs (referred as minute hairs when less than 0.5 mm long), usually mixed with patent stinging (urticating) hairs. Leaves alternate, petiolate, stipulate, pulvinate (distally and/or proximally), simple, with an entire, dentate to serrate or sinuate (in T. volubilis) margin, cordate or rounded base, acute or acuminate apex, not ciliate, membranous, palmatinerved, without stipels. Inflorescences terminal, leaf-opposed or lateral, rarely axillary, racemose, unisexual or bisexual, with 1–2(3) female flowers at the base; bracts conspicuous, persistent, 1–3-flowered; bracteoles 2 (male flowers sometimes without). Male flowers pedicellate (pedicel articulate); calyx closed in bud, later splitting into 3 valvate lobes; petals 0; disk 0; stamens (2)3, filaments short, anthers 2-thecous, dorsifixed or almost basifixed, longitudinally dehiscent, connective narrow. Female flowers pedicellate (pedicel articulate); calyx with 3 or 6 lobes, imbricate, entire or laciniate to pinnatifid or subpalmatifid, persistent and reflexed in fruit, slightly or strongly accrescent, the median portion becoming indurated; petals 0; disc 0; ovary 3-locular, oblate, with 1 ovule per locule, smooth; styles 3, connate at the base into a short, slender column, free above, entire. Fruits 3-lobed, dehiscent into 3 2-valved cocci (rarely also monocarpous allomorphic and horned, in T. volubilis), smooth; cocci subglobose; endocarp crustaceous; columella 3-fid, persistent. Seeds globose, ecarunculate, smooth; testa crustaceous.

Key to the Tragia species in Gabon

1. Inflorescence unisexual; calyx lobes entire in fruit, not strongly accrescent 2
– Inflorescences bisexual; calyx lobes laciniate or dentate (1–3 teeth) in fruit, strongly accrescent 3
2. Branches with stinging hairs; leaf blade oblong, elliptic to ovate-lanceolate, truncate to cordate base, serrate, secondary veins in 4–5 pairs; male inflorescences up to 1.5 cm long; calyx lobes of female flower 1.5 mm long T. volubilis
– Branches without stinging hairs; leaf blade elliptic to obovate, rounded base, entire to slightly dentate, secondary veins in 7–8 pairs; male inflorescences up to 16.5 cm long; calyx lobes of female flower 3–3.5 mm long T. flagellata
3. Leaf blade ovate; calyx lobes laciniate in fruit, without foliaceous laminula T. benthamii
– Leaf blade elliptic-lanceolate, obovate-lanceolate to oblanceolate; calyx lobes lobulate in fruit, with foliaceous laminula 4
4. Branches without stinging hairs; stipules ovate-cordate; inflorescence with 2–3 female flowers with entire bracts in the basal part T. sericea
– Branches with stinging hairs; stipules triangular-lanceolate; inflorescence with 1–2 female flowers with dentate or lobate bracts in the basal part 5
5. Leaf blade (5.5–)8–11.5 cm long, obovate-lanceolate; female bracts deeply trilobate; styles 3.5–4 mm; calyx lobes up to 6 mm long in fruit, with elliptic foliaceous laminula T. mildbraediana
– Leaf blade 4.2–8.4 cm long, elliptic; female bracts distally regularly 3–4 dentate to 1/3 of the length; styles 0.7–1 mm; calyx lobes up to 4 mm long in fruit, with oblanceolate foliaceous laminula T. zenkeri

Tragia benthamii Baker (Baker 1910: 128)

Fig. 1A

Type

EQUATORIAL GUINEA – Bioko Norte • Port Clarence; 1843; Vogel T. 26; lectotype (designated here): K [K000425676] image; isolectotype: K [K000425677] image.

Syntypes

ANGOLA – Luanda • s.loc.; s.d.; Gossweiler 427; LISU [LISU60223, LISU60224]. – Cuanza Norte • Golungo Alto; Welwitsch 381; COI [COI00111766] image, G [G00325734] image. – Unknown province • s.loc.; s.d.; Monteiro s.n.; K [K005273042] image.

CAMEROON • s.loc.; s.d.; Mann 1255; not found • s.loc.; s.d.; Zenker & Staudt 516; B†, BR [BR0000016243125] image, COI [COI00111767] image.

GHANA – Ashanti Region • s.loc.; 1895; Cummins s.n.; not found. – Unknown region • s.loc.; 1843; Vogel 53; K [K000425674, K000425675] images.

MALAWI – Central Region • Namasi [Nyamazi?]; s.d.; Cameron s.n.; not found.

NIGERIA – Ogun State • Abeokuta; Millen 80; not found.

UGANDA • s.loc.; s.d.; Dawe 5; not found.

Description

Straggling or twining and scandent herb or shrub of unknown height; young branches puberulous with appressed hairs and stinging hairs up to 1.4 mm long; mature branches glabrescent. Stipules triangular, 3–4 × 0.8–1.2 mm, acute, glabrous, ciliate with erect hairs up to 0.5 mm long. Petioles (1.8–)2–5 cm long, densely pubescent with appressed hairs and stinging hairs up to 1.4 mm long; distally and proximally pulvinate. Leaf blade ovate, (4–)4.5–8.4 × (2.2–)2.8–5.8 cm, cordate at base, acuminate at apex, with acumen up to 0.8 cm, dentate-serrate, upper surface hispid with stinging hairs up to 1.5 mm long, with appressed hairs mainly on veins, lower surface indumentum similar to that found on the upper surface but less dense, basal veins 7, secondary veins 4–5 pairs. Inflorescences bisexual, up to 5.5 cm long; peduncle up to 3.5 cm, pubescent with curved, appressed hairs. Male segment 0.6–3.5 cm long; bracts elliptic, ca 1.5 × 0.4 mm, glabrous; bracteoles linear-lanceolate, 0.4 × 0.1 mm, glabrous. Female segment with 2 flowers; bracts triangular, entire, acute, 2 × 0.8 mm, glabrous; bracteoles linear-lanceolate, 1.1 × 0.2 mm, glabrous. Male flower pedicel up to 1.1 mm long, sparsely hairy, with few scattered minute appressed hairs; buds ca 0.4 mm diameter; calyx lobes 0.8 mm long, sparsely hairy externally, with few scattered minute, appressed hairs; stamens 3; filament up to 0.2 mm long; anthers 0.2 × 0.2 mm. Female flower subsessile; pedicel up to 0.3 mm long, pubescent with curved, minute, appressed hairs; calyx with 6 lobes, largely laciniate to the base (7 segments), 1–3.5 mm long, pubescent externally, with minute stinging hairs; ovary 0.4 × 0.8 mm, densely hispid with stinging hairs; styles 1.2–3 mm, connate 2/3 of the length, glabrous. Fruits subsessile, with peduncle up to 0.3 mm long, 3 × 5 mm, hispid, with stinging hairs up to 1.5 mm long; calyx lobes deeply laciniate, ca 6.5 mm long, 4–6 segments on each side, without laminula, slightly hardened in the central part, hispid, with stinging hairs up to 1.5 mm long; columella up to 2 mm long. Seeds 3 mm in diameter, yellowish mottled with black.

Distribution

Widely distributed in tropical Africa: Angola, Benin, Botswana, Cameroon (Fig. 1A), Central African Republic, Republic of the Congo, Democratic Republic of the Congo, Equatorial Guinea (Fig. 1A), Ethiopia, Gabon (Fig. 1A), Ghana, Ivory Coast, Malawi, Mozambique, Nigeria, South Sudan, Togo, Uganda, Zambia, and Zimbabwe (Keay 1958; Radcliffe-Smith 1987, 1996; Cable and Cheek 1998; Cheek et al. 2000, 2004; Akoègninou et al. 2006; Govaerts et al. 2000; Sosef et al. 2006; Figueiredo and Smith 2008; Barberá et al. 2013; Pickering and Darbyshire 2015).

Figure 1. 

Distribution map of Tragia benthamii (A) and T. flagellata (B) in Cameroon, Gabon, and Equatorial Guinea.

Habitat and ecology

It grows on the edges of savanna or secondary forest and in open areas (in plantations) at 40–2060 m elevation.

Additional material examined

CAMEROON – Adamawa Region • Gallery forest near falls in Tello River, about 47 km E of Ngaoundéré, on moist places in shade; [7°13’46”N, 13°56’30”E]; 1200 m; 27 Nov. 1964; de Wilde 4314; BR [BR0000016243118] image. – Centre Region • Pentes de la colline Mbere près Matsari, SSO de Yoko; [5°32’01”N, 12°19’17”E]; 28 Oct. 1977; Biholong 327; BR [BR0000016248694] image • Afanetabini, 20 km E d’Obala; [4°09’31”N, 11°32’11”E]; 6 Nov. 1969; Letouzey 9514; BR [BR0000016243101] image. – East Region • Bertoua, 25 km along road to Nanga-Eboko, roadside, edge of native plantation; [4°33’48”N, 13°23’51”E]; 5 Nov. 1960; Breteler 610; BR [BR0000016243088] image, WAG [WAG.1338747] image. – Litoral Region • Lake Manenguba, crater of Female Lake; 5°00’N, 9°50’E; 1975 m; 5 Feb. 1995; Cheek 7273; K [K000026606] image • West of Kodmin up to 3 km along road to Loh Mt.; 5°00’N, 9°47’E; 1450 m; 13 Nov. 1998; Cheek 9605; K [K000026605] image. – North-West Region • Turkod; 5°48.96’N, 10°05.68’E; 15 Nov. 2000; Biye 125; K [K000746230] image • Lus; [6°40’59.9”N, 10°58’00”E]; 650 m; s.d.; Baeke 151; BR [BR0000015822154] image • Afua swamp to Afua junction; 6°09’N, 10°22’E; 7 Dec. 1998; 1800 m; Cheek 9859; K [K000338913] image • Bamenda, Bu, Ketse’e, near the waterfall; 6°16’N, 10°06’E; 625 m; 14 Nov. 2000; Ghogue 1112; K [K001480101] image • Kumbo (= Banso); [6°12’N, 10°04’E]; 14 Feb. 1958; Hepper 1979; K [K000181250] image • Bamenda Highlands; [6°30’00”N, 10°39’59”E]; 1950 m; 11 Dec. 1998; Maisels 214; K [K000875928] image • Upkim Traditional Forest; [6°12’48”N, 10°42’35”E]; 2060 m; 4 Nov. 1996; Munyenyembe 870; K [K000338909] image • Bui, Blak-Oku; 6°15’N, 10°26’E; 6 Nov. 1996; Onana 500; K [K000338910] image • Boyo, Aboh village; 6°15’N, 10°26’E; 1600–1700 m; 24 Nov. 1996; Onana 606; K [K000338911] image • Boyo, Aboh, Ijim Mountain Forest; 6°06’42”N, 10°15’15”E; 21 Nov. 1996; Pollard 78; K [K000338912] image. – South Region • 16 km on the road from Ebolowa to Minkok, shortcut on the road to M’Balmayo, old cacao plantation along the road; [2°57’35”N, 11°18’11”E]; 2 Sep. 1975; de Wilde 8436; BR [BR0000016243071] image. – South-West Region • Bakossi Mts. Kodmin, 0.5 km on road to Ndip; 4°60’N, 9°42’E; 1500 m; 18 Jan. 1998; Cheek 8889; K [K000026604] image • Kodmin, west of Kodmin up to 3 km along road to Loh Mt.; 5°00’N, 9°47’E; 1450 m; 13 Nov. 1998; Cheek 9605; BR [BR0000025342147V] image, K [K000026605] image, KUPE n.v., YA n.v. • Lake Edip; 4°57’N, 9°39’E; 21 Nov. 1998; Etuge 4494; K [K000026607] image • Buea district; [4°9’00”N, 9°13’60”E]; Jan. 1929; Maitland 238; K [K000181249] image • Buea; [4°09’00”N, 9°13’60”E]; 9 Nov. 1927; Migeod 104; K [K000181248] image.

EQUATORIAL GUINEA – Bioko Norte • Malabo-Bahia de Venus; [3°45’22”N, 8°46’28”E]; 18 Oct. 1989; Carvalho 4142; MA [MA-700067]. – Litoral • Bata-Mongo-Zona Florestal de Alosa, estrada kms 57–58 entre Mongo e Serração de Alosa; [1°25’60”N, 9°46’60”E]; 10 Nov. 1993; Carvalho 5420; MA [MA-598450], MO [MO-3644753].

GABON – Estuaire • 49 km ESE of Libreville, along Komo River, Ngaba; 0°10.44’N, 9°48.65’E; 40 m; 3 Mar. 2013; Wieringa 7048; WAG [WAG.1338991] image. – Ogooué-Ivindo • Route Makokou-Mékambo, km 7; 0°36’N, 12°55’E; 500 m; 2 Mar. 1979; Florence 1690; P [P04839708] • Lope National Park; 0°06’25”S, 11°41’16”E; 100 m; 19 Apr. 2006; Leal 1137; MO [MO-3644754], WAG • Mékambo-Mazingo Road; 1°10.9’N, 14°07.2’E; 525 m; 23 Jan. 2018; Texier 1963; BRLU, LBV, MO, P, WAG. – Unknown province • s.loc.; 4 Jan. 1885; Thollon 143; P [P04839706].

Notes

We have selected the specimen Vogel 26 (K000425676) as the lectotype of Tragia benthamii because it includes all the morphological details for a proper identification, besides being the best-preserved preparation.

After a careful revision of the West African material and considering the comments made by Radcliffe-Smith (1987), we think that T. benthamii should be treated as a species restricted to West, Central, and South-central tropical Africa, from Ivory Coast to Nigeria, and from the Central African Republic and the Democratic Republic of the Congo to Angola and Zambia. The study of the material from East and Southern Africa is still pending to confirm or refute its presence in those regions. Accordingly, we have confirmed that the material previously identified as T. benthamii from Ethiopia belongs to T. mitis Hochst. ex A.Rich., while Kenyan material belongs to T. keniensis Rendle (included as a synonym of T. benthamii by Govaerts et al. 2000).

Tragia benthamii and T. brevipes Pax, occurring in Cameroon and from the Democratic Republic of the Congo eastwards (Radcliffe-Smith 1987, 1996), have morphological similarities but can be well differentiated. Tragia benthamii may be recognised by its puberulous branches with appressed simple hairs and stinging hairs up to 1.4 mm long (vs branches densely or sparsely pubescent and sparingly armed with stinging hairs), leaves sparsely hispid with stinging hairs and with appressed hairs mainly on veins on both surfaces (vs leaves sparsely pubescent above, and densely pubescent, almost velvety, beneath and sparingly armed with stinging hairs on both surfaces especially on nerves), stipules 3–4 mm long, glabrous, ciliate with erect hairs (vs stipules 2–3 mm long, densely pubescent externally), and calyx lobes ca 6.5 mm long in fruit, hispid with stinging hairs, and without laminula (vs calyx lobes up to 1.2 cm long in fruit, externally densely pubescent with not stinging and stinging hairs, with laminula narrowly lanceolate or subulate).

Tragia flagellata I.Montero & Barberá, sp. nov.

urn:lsid:ipni.org:names:77369356-1
Figs 1B, 2

Type

GABON – Woleu-Ntem • Minkébé region, Nsye valley; 1°30’N, 12°49’E; 23 Feb. 1990; Wieringa 617; holotype: WAG [WAG.1338914]; isotypes: BR [BR0000016245433] image, C n.v., K [K005272502] image, LBV, M n.v., MO [MO-4496777], PRE n.v., WAG [WAG.1338915].

Diagnosis

Tragia flagellata is morphologically close to T. liberica Jongkind, but differs mainly by having unisexual inflorescences (vs bisexual inflorescences), and the calyx of female flowers (seen in fruit) with triangular and entire sepals (vs calyx of female flower with pinnatisect sepals).

Description

Twining perennial herb or shrub up to 5 m high; young branches pubescent with curved, appressed hairs up to 0.5 mm long; mature branches glabrescent. Stipules triangular-lanceolate, 3–4.5 × 0.8–1.1 mm, acuminate, sparsely hairy externally, with hairs up to 0.3 mm long, not ciliate. Petioles 0.6–1.7 cm long, densely pubescent with curved, appressed hairs up to 0.5 mm long; proximally pulvinate. Leaf blade elliptic to obovate, 7.5–14 × 2.5–4.5 cm, rounded at base, acuminate at apex, with acumen up to 1 cm, entire to slightly dentate, upper surface subglabrous, with simple subulate hairs up to 0.5 mm long and with stinging hairs up to 0.8 mm long mainly on veins; lower surface pubescent with stinging hairs up to 0.8 mm long on veins and up to 0.5 mm long on the lamina; basal veins 3–5, secondary veins in 7–8 pairs. Inflorescences unisexual. Male inflorescence up to 16.5 cm long; peduncle 8–9 cm long, densely pubescent with curved hairs up to 0.2 mm long that extend to the rachis; bracts narrowly triangular, 1.3–1.6 × 0.2-0.3 mm, sparsely hairy with hairs up to 0.1 mm long; bracteoles linear-lanceolate, 0.3–0.5 × 0.1 mm, subglabrous with few scattered hairs. Male flower pedicel 1.1–2.4 mm long, subglabrous with few scattered hairs; buds 0.4–0.5 mm diameter; calyx lobes broadly ovate to broadly elliptic, 0.7 mm long, pubescent externally; stamens 3; filament 0.15 mm long; anthers 0.2 × 0.15 mm. Female inflorescence up to 1.7 cm, peduncle up to 1.2 cm long, glabrescent, with 1–3 flowers; bracts ovate, 2 mm long, sparsely pubescent. Female flowers unknown. Fruits partially known; peduncle 3.5 mm long, pubescent; calyx lobes 6, triangular, up to 3.5 mm long, entire, slightly hardened when mature, sparsely pubescent with long thin hairs externally, with a distinct central vein; columella 3 mm long. Seeds unknown.

Distribution

Currently only known from Gabon, from the Woleu-Ntem and Ogooué-Ivindo provinces (Fig. 1B).

Habitat and ecology

It grows in periodically inundated low forest (shrub vegetation behind riverbank) at ca 500–700 m elevation.

Etymology

The specific epithet, flagellata, is derived from the Latin flagellum (whip, scourge), and refers to the length of the male inflorescences and their whip-like resemblance.

Preliminary IUCN conservation assessment

Endangered: EN B2ab(iii). Tragia flagellata is known from two collections, made in 1966 and 1990, representing two occurrences and two subpopulations, which are both expected to be still extant. The area of occupancy (AOO) of this species is estimated as 8 km2 (sensu IUCN 2022), which is below the upper threshold for a Critically Endangered status under subcriterion B2. The extent of occurrence (EOO) cannot be calculated. The northernmost occurrence in the Nsye Valley (Wieringa 617) is situated at the limits of a mining concession, threatened by mining; the occurrence from Belinga (Hallé 422) is located in mining and forestry concessions, threatened by mining and logging. As a consequence, these two occurrences represent two locations concerning the most serious plausible threat (mining). We infer a current and future continuous decline in the extent and quality of its habitat. Tragia flagellata is thus provisionally assessed as Endangered: EN B2ab(iii).

Figure 2. 

Tragia flagellata. A. Habit. B. Leaf lower surface detail. C. Stipule and petiole. D. Male part of the inflorescence detail. E. Male bract and flower. F. Female inflorescence detail with columella. G. Fruit calyx. Drawn by Hilde Orye, Meise Botanic Garden, based on Wieringa 617 (WAG.1338914, WAG.1338915).

Additional material examined

GABON – Ogooué-Ivindo • Bélinga, mines de fer, route du camp; [1°06’N, 13°12’E]; 11 Aug. 1966; Hallé 422; K [K005272493] image, P [P04839871], WAG [WAG.1339084].

Notes

Tragia flagellata is morphologically similar to Tragia preussii, another species from the surrounding countries (Cameroon and the Democratic Republic of the Congo). The collection Wieringa 617 was cited in the National Checklist (Sosef et al. 2006) as cf. T. preussii and this was the only record of this species in Gabon. Jongkind (2015) was the first author to suggest that this material could correspond to an undescribed species; he indicated that the female flowers are not in the same inflorescences as the male ones (like in T. volubilis). Here we confirm this character by reviewing all the available material (duplicates and one new collection found, Hallé 422). Tragia flagellata differs mainly by having unisexual inflorescences (vs bisexual inflorescences), and female flower calyx lobes triangular and entire (vs female flower calyx lobes deeply lobulate, with 3–4 lobes at each side).

This new species is still imperfectly known (female flowers and seeds are unknown, while fruits are partially known), but it is quite distinctive.

Tragia mildbraediana Pax & K.Hoffm. (Pax and Hoffman 1919: 96)

Figs 3, 4A

Type

CAMEROON – East Region • Molundu [Moloundou] am Dscha [by the Dja]; [2°02’46”N, 15°12’49”E]; 23 Nov. 1910; Mildbraed 3899; lectotype (designated here): HBG [HBG515788] image.

Description

Twining perennial herb of unknown height; young and mature branches hispid with stinging hairs up to 1 mm long. Stipules triangular-lanceolate, 6–7.5 × 2.1 mm, acute, subglabrous externally, ciliate with hairs up to 1.5 mm long. Petioles (0.4–)1.2–2.7 cm long, hispid with stinging hairs up to 1 mm long; distally pulvinate. Leaf blade obovate to elliptic, (5.5–)8–11.5 × (2.8–)3.7–5.8 cm; rounded to slightly cordate at base, acuminate at apex, with acumen up to 0.5 cm, slightly dentate, upper surface sparsely hairy with stinging hairs up to 1 mm long, lower surface indumentum similar to that found on the upper surface but denser on veins, basal veins 3–5, secondary veins in 5–6 pairs. Inflorescences bisexual, up to 3.5 cm; peduncle up to 1.8 cm, hispid, with stinging hairs up to 0.5 mm long. Male segment up to 1.5 cm long; bracts obovate-lanceolate to obovate, apically sinuate or crenate, acute, sometimes irregularly dentate (2–3 teeth), 2.8 × 1.1 mm, sparsely hairy with short hairs, ciliate with hairs up to 0.5 mm long; without bracteoles. Female segment with 1 flower; bracts deeply trilobate with lobes ovate-lanceolate (longer one 4 × 1 mm long), sparsely hairy, ciliate (with hairs up to 0.5 mm long); bracteoles ovate-elliptic, 2 × 1.2 mm, sparsely hairy with scattered hairs externally, ciliate with short hairs up to 0.5 mm long. Male flower pedicel ca 2 mm long, slightly puberulous, with short hairs up to 0.1 mm long; buds ca 0.8 mm in diameter; calyx lobes 0.4 mm long, slightly puberulous, with minute hairs; stamens 3; filament ca 0.2 mm long; anthers 0.15 × 0.2 mm. Female flower sessile; calyx with 6 lobes, elliptic, with 1–2 teeth on each side, 2 × 1 mm, pubescent, with hairs ca 0.8 mm long; ovary 2 × 1 mm, densely hispid; styles 3.5–4 mm, connate until the middle, sparsely hairy. Fruits sessile, 5.5 × 8 mm, densely pubescent, with hairs up to 0.8 mm; calyx lobes lobulate, up to 6 mm long, with 1–3 teeth on each side, with laminula elliptic 2(–3) × 1 mm, slightly hardened in the central part, pubescent, with short hairs up to 0.8 mm long; columella 3 mm long. Seeds 3 mm in diameter, light brown with dark brown patches.

Figure 3. 

Tragia mildbraediana. A. Habit. B. Inflorescence with immature fruit. Photos by Nicolas Texier.

Distribution

Cameroon (Pax and Hoffmann 1919), Equatorial Guinea, Gabon, and Republic of the Congo (Fig. 4A).

Figure 4. 

Distribution map of Tragia mildbraediana (A) and T. sericea (B) in Cameroon, Gabon, and Equatorial Guinea.

Habitat and ecology

This species grows in open secondary forests at 5–680 m elevation.

Additional material examined

CAMEROON – East Region • 17 km N of Bertoua, along road to Deng Deng; [4°43’15”N, 13°37’10”E]; 680 m; 6 Jan. 1962; Breteler, de Wilde & Leeuwenberg 2417; BR [BR0000016248816] image, WAG [WAG.1338866, WAG.1338868] images • 15 km E of Dimako; [4°20’43”N, 13°41’59”E]; 650 m; 13 Dec. 1965; Leeuwenberg 7328; BR [BR0000016249080] image, WAG [WAG.1338864, WAG.1338865, WAG0144378] images • A 4 Km au SSW de Koso (village situé à 60 Km au SSW de Batouri); [3°55’33”N, 14°09’01”E]; 29 Jul. 1963; Letouzey 5535; P [P00346743] image.

EQUATORIAL GUINEA – Bioko Norte • Malabo, aeroporto, estrada km 6; 32NMK7014; 26 Sep. 1986; Carvalho 2510; MA [MA-716364] • Entre Malabo y el aeropuerto, junto al km 6 de la autopista; 32NMK6915; 7 Jul. 1986; Fernández Casas 10254; MA [MA-699764].

GABON – Estuaire • Parc National de la Pongara, camp de Gabon Environnement, Pointe Ouingombé; 0°19.7’N, 9°19.2’E; 5 m; 20 Mar. 2007; Dauby 219; BRLU, LVB, MO. – Ogooué-Ivindo • Mwagna National Park and peripheric area, northeast of national park around the Mabekwe camp; 0°36’05”N, 13°49’52”E; 502 m; 19 Jan. 2018; Texier 1868; LVB, MO. – Woleu-Ntem • Mont Miwa, inselberg a 3 km du village de Kumassi, a 35 km d’Oyem vers Bitam; 1°50’N, 11°38’E; 680 m; 15 Apr. 2002; Parmentier 2563bis; BRLU.

REPUBLIC OF THE CONGO – Bouenza • Loudima, bord de l’eau; [4°06’46”S, 13°04’44”E]; 1 Oct. 1950; Koechlin 1379; IEC [IEC008051]. – Sangha • District de Ngbala, UFA Tala Tala, Forêt de Godha; [1°24’02”N, 15°20’07”E]; 433 m; 6 Aug. 2010; Nsongola 278; IEC [IEC026530, IEC026531] • District de Souanké, ca 52 km SW of Souanké along Garabinzam road, Bessié village (near ”Koulmélen”); [1°56’N, 13°54’E]; 510 m; 9 Nov. 1991; Thomas 8810; WAG [WAG.1338875] image.

Notes

We have selected the specimen Mildbraed 3899 (HBG515788) as the lectotype of Tragia mildbraediana because it was the only original material found.

Tragia mildbraediana is a relatively little-known species, newly reported here for Gabon, Equatorial Guinea, and the Republic of the Congo. After a preliminary revision of material from West Africa, we confirm that this species is not present in Ghana, Ivory Coast, or Liberia (Govaerts et al. 2000).

Tragia mildbraediana coexists with T. zenkeri, from which it can be distinguished by its obovate-lanceolate leaves of 9–11.5 × 3.7–5.8 cm (vs leaves elliptic, 4.2–8.4 × 2.3–3.8 cm), deeply trilobate female bracts, with ovate-lanceolate lobes, ca 3.5 mm long (vs female bracts subcuneate distally 3–4-dentate until 1/3 of the length, ca 1.5 mm long), the styles connate to the middle, up to 4 mm long (vs styles connate at the base, up to 1 mm long), and calyx lobes up to 6 mm long in fruit, with laminula elliptic 2(–3) × 1 mm (vs calyx lobes ca 4 mm long in fruit, with laminula oblanceolate 1.5(–2) × 1(–1.5) mm).

Tragia mildbraediana is morphologically similar to T. sericea, but can be distinguished by its obovate-lanceolate leaves of 9–11.5 × 3.7–5.8 cm (vs elliptic-lanceolate to oblanceolate, 5–8 × 3–4.4 cm), deeply trilobate female bracts, with ovate-lanceolate lobes (vs bracts of the female flower obovate with entire margin), branches hispid with simple, subulate stinging hairs up to 1 mm long (vs. branches pubescent with minute retrorse, appressed hairs), and calyx lobes up to 6 mm long in fruit, with laminula elliptic 2(–3) × 1 mm (vs calyx lobes up to 2.5 mm long in fruit, with laminula lanceolate 1.3 × 1 mm).

Tragia sericea I.Montero & Barberá, sp. nov.

urn:lsid:ipni.org:names:77369357-1
Figs 4B, 5

Type

GABON – Ogooué-Maritime • Route en construction Port-Gentil-Omboué, env. 5 km au sud du pont sur l’Ogooué; 1°05.22’S, 8°56.54’E; 26 Nov. 2016; Lachenaud 2354; holotype: P [P01193100]; isotypes: BR, BRLU, LBV, MO, WAG.

Diagnosis

Tragia sericea is morphologically similar to T. zenkeri Pax, but differs mainly by having branches and petioles without stinging hairs (only appressed, curved, retrorse hairs) (vs branches and petioles with short and not stinging and stinging hairs), female flower with entire obovate bracts (vs subcuneate, regularly dentate in the upper third with 3 or 4 teeth on either side), and stipules ovate-cordate (vs stipules triangular-lanceolate).

Description

Twining perennial herb of unknown height; young and mature branches pubescent with retrorse, appressed hairs up to 0.3 mm long. Stipules ovate-cordate, ca 4.7 × 2.3 mm, acute, hairy externally, ciliate with hairs up to 0.5 mm long. Petioles 1.5–3.5 cm long, pubescent with curved, appressed hairs up to 0.3 mm long; distally and proximally pulvinate. Leaf blade elliptic to oblanceolate, (4–)5–8 × (2.2–)3–4.4 cm, cordate at base, acuminate at apex, with acumen up to 1 cm, subentire to slightly serrate, with few tufted hairs at the teeth apex, upper surface subglabrous, sparsely hairy with stinging hairs up to 0.5 mm long on the main veins, lower surface sparsely hairy with stinging hairs up to 0.5 mm long, densely on veins; basal veins 5, secondary veins in 4–5 pairs. Inflorescences bisexual, up to 4 cm long; peduncle up to 2 cm, pubescent with minute, curved, appressed hairs. Male segment up to (1–)1.5–2 cm long; bracts oblanceolate, 1.3 × 0.5 mm, sparsely hairy and ciliate with minute hairs; without bracteoles. Female segment with 2–3 flowers; bracts obovate, 1.7–2.1 × 1.7–2 mm, sparsely hairy externally with minute hairs, entire, ciliate with minute hairs; bracteoles lanceolate, 1.9 × 0.5 mm, sparsely hairy externally with minute hairs, ciliate with minute hairs. Male flower pedicel up to 1.5 mm long, sparsely hairy with few scattered hairs; buds to 0.9 mm diameter; calyx lobes 0.7 mm long, glabrous; stamens 3; filament ca 0.3 mm long; anthers 0.3 × 0.3 mm. Female flower subsessile; pedicel up to 0.4 mm long, pubescent with minute, curved hairs; calyx lobes 6, oblanceolate, entire, sometimes with a very small tooth near the base, 1.8 × 0.8 mm, sparsely hairy externally, ciliate with minute hairs; ovary 0.6 × 1.3 mm, densely hispid; styles up to 1.7 mm, connate until 2/3 to 1/2 of the length, sparsely hairy with minute hairs. Fruits on an up to 1.5 mm long peduncle, 4.5 × 6.5 mm, pubescent with stinging hairs up to 1 mm long, and not stinging too; calyx lobes up to 2.5 mm long, lobulate, laminula lanceolate, 1.3 × 1 mm, with 1–3 small linear sparsely hairy lobules on each side, hardened in the central part, sparsely hairy with very short hairs, ciliate; columella 2 mm long. Seeds 2 mm in diameter, black with yellowish patches.

Figure 5. 

Tragia sericea. A. Habit. B. Detail of a twining stem. C. Leaf lower surface and inflorescence detail. D. Inflorescence with male flowers and immature fruit. E. Inflorescence with mature fruit. Photos by Olivier Lachenaud.

Distribution

Equatorial Guinea, Gabon, and the Republic of the Congo (Fig. 4B).

Habitat and ecology

It grows in littoral forest and other littoral vegetation, on white sand, at 10–21 m elevation.

Etymology

The specific epithet, sericea, is derived from the Latin sericeus (silky, silk), and refers to the lack of erect stinging hairs on the branches, which gives it a soft appearance.

Preliminary IUCN conservation assessment

Vulnerable: VU B2ab(iii). Tragia sericea is known from 11 collections made between 1897 and 2016, representing 10 occurrences and seven subpopulations. The area of occupancy (AOO) is estimated as 36 km2, below the upper threshold for Endangered status under subcriterion B2. The extent of occurrence (EOO) is calculated as 68,109 km2, exceeding the upper threshold for “Vulnerable” status under subcriterion B1. The occurrence from Equatorial Guinea is located close to the road and threatened by the road constructions. In Gabon, the two occurrences from the Estuaire province, from the surroundings of Libreville, are threatened by urbanisation; in the Ogooué-Maritime province, the northernmost occurrence is close to the road in construction from Port Gentil to Omboué and is threatened by road construction; the southernmost occurrence is located inside the Moukalaba-Doudau National Park, and it is not threatened; the four occurrences from the Nyanga province are included in the Gamba Protected Area Complex, but threatened by shifting agriculture. The two occurrences from Republic of the Congo from Kouilou province are threatened by shifting agriculture. As a consequence, these ten occurrences represent seven locations, concerning the most serious plausible threat (shifting agriculture). We infer a current and future continuous decline in the extent and quality of its habitat. Tragia sericea is thus provisionally assessed as Vulnerable: VU B2ab(iii).

Additional material examined

EQUATORIAL GUINEA – Litoral • Bata-Bome, pradera graminosa con longo do Rio Boara con ilhas arboreas arbustivas formadas pelas especies; [1°45’N, 9°45’E]; 8 Oct. 1991; Carvalho 4867; MA [MA-597380].

GABON – Estuaire • 8 km N Libreville; [0°25’N, 9°27’E]; 30 Jan. 1961; Hallé 0969; P [P04839873] • Environs de Libreville; [0°25’N, 9°27’E]; 1897; Klaine 743; P [P04808441]. – Nyanga • Gamba, Pont Dick, 3.6 km SW of Gamba airport; 2°48.5’N, 10°02.8’E; 300 m; 29 Nov. 1994; de Wilde 11240; BRLU, E n.v., LBV, M n.v., MO [MO-4496803], WAG [WAG.1338861, WAG.1338862] • Near Ivinga 23; 2°48.00’S, 10°03.05’E; 31 Dec. 1990; van Nek 514; LVB, WAG [WAG.1338856] • Gamba, 4 km ESE of airport, road to radio mast; 2°48.01’S, 10°04.07’E; 10 m; 19 Mar. 1994; Wieringa 2600; BR, G [G00351141], LBV, MA [MA-859889], MO [MO-4496804], P, W [W2013-0009087], WAG [WAG.1338858, WAG.1338859, WAG.1338860]. – Ogooué-Maritime • Side roads of road Pény-Mouila, in CBG concession; 2°02.0’S, 9°25.5’E; 21 m; 10 Nov. 2011; Maas 10194; LBV, UC [UC2106923], WAG [WAG.1339083].

REPUBLIC OF THE CONGO – Kouilou • Conkouati, Douli, forêt sur sable blanc a 200 m du village Vandji; [4°02’07.7”S, 11°15’46.9”E]; 3 m; 11 Dec. 2012; Mpandzou 1857; IEC n.v., K [K000609803] (image) • Plage Longo, Boudji; [4°18’28.9”S, 11°31’03.8”E]; 12 Dec. 2012; Mpandzou 1893; IEC n.v., K [K000609799] (image).

Notes

Specimens of T. sericea were previously identified as T. tenuifolia or T. laminularis, due to the similarity to those species. Tragia tenuifolia seems endemic to São Tomé and does not occur in Gabon, while T. laminularis occurs only in Ivory Coast and Liberia. The new species is morphologically similar to T. mildbraediana (see Notes with T. mildbraediana).

All the specimens cited by Sosef et al. (2006) as T. laminularis (de Wilde 11240, Nek 514, 735, Wieringa 2600) and T. tenuifolia (Klaine 743) belong to T. sericea.

Tragia volubilis L. (Linnaeus 1753: 980)

Fig. 6A

Type

JAMAICA • s.loc.; s.d.; Herb. Linn. No. 1103.1; lectotype (designated by Radcliffe-Smith 1987): LINN [LINN 1103.1].

Description

Scandent perennial herb up to 1.5 m high; young and mature branches pubescent with stinging hairs up to 0.5 mm long. Stipules lanceolate, 3.5–4 × 1–1.5 mm, acute, subglabrous, ciliate with hairs up to 0.3 mm long. Petioles (0.5–)1–4(–6) cm long, sparsely hairy with hairs up to 0.5 mm long; distally and proximally pulvinate. Leaf blade oblong-lanceolate to elliptic or ovate-lanceolate, (3–)4–10(–11) × (2–)3–4.5 cm, truncate to cordate at base, acute to subacuminate at apex, with acumen up to 1 cm long, mucronate, serrate, upper surface sparsely hairy with stinging hairs up to 0.5 mm long, lower surface similar to upper surface; basal veins 5, secondary veins in 4–5 pairs. Inflorescences unisexual. Male inflorescences up to 1.5 cm long, peduncle up to 0.5 cm, subglabrous with minute hairs; bracts ca 1 mm long, narrowly lanceolate, subglabrous; bracteoles similar to bracts. Male flower pedicel ca 2 mm long, glabrous; buds 0.5 mm diameter; calyx lobes narrowly ovate, 0.5 mm long, glabrous; stamens 2–3; filaments up to 0.2 mm long; anthers 0.3 × 0.2 mm. Female inflorescences up to 3 cm long, peduncle up to 2.5 cm long, pubescent with stinging hairs up to 0.5 mm long, with 1 flower; bracts up to 1 mm long, narrowly lanceolate, subglabrous; bracteoles similar to the bracts. Female flower subsessile; calyx lobes 6, lanceolate, entire, 1.5 mm long, glabrous; ovary 1.5 × 2 mm, densely hispid with stinging hairs up to 1 mm long; styles ca 1.5 mm long, connate until 1/2 length, glabrous. Fruits dimorphic, regular fruits trilobate, 4 × 6 mm, densely hispid with stinging hairs up to 1 mm long; fruits allomorphic monococcus with 2–3 prominent horns up to 0.8 cm long, hispid with stinging hairs up to 1 mm long; calyx lobes 6, up to 1.5 mm long, lanceolate, entire, without laminula, not hardened, subglabrous; columella 2 mm long. Seeds 3 mm diameter, light brown with black patches.

Distribution

Originally from the Americas, widely distributed in Africa (Prain 1913; Keay 1958; Radcliffe-Smith 1987, 1996; Sosef et al. 2006; Figueiredo and Smith 2008; Cheek et al. 2011; Barberá et al. 2013) (Fig. 6A).

Figure 6. 

Distribution map of Tragia volubilis (A) and T. zenkeri (B) in Cameroon, Gabon, and Equatorial Guinea.

Habitat and ecology

It grows in rainforest, mostly secondary, mangroves, and scrubland at 0–710 m elevation.

Additional material examined

CAMEROON – Centre Region • Ndanan I to Ndanan II, Raphia swamp; 03°36’53”N, 11°34’20”E; 710 m; 16 Mar. 2004; Cheek 11783; K [K000678378] image • N’Kolbisson, near Yaoundé; [3°52’14”N, 11°27’16”E]; 700 m; 2 Nov. 1964; de Wilde 3708; BR [BR0000016246416] image. – South Region • Dja et Lobo Dept. Koulaze, 71 km SE of Akonolinga; 03°08’N, 12°28’E; 650 m; 26 Feb. 1996; Nkongmeneck 1541; MO [MO-4236213].

EQUATORIAL GUINEA – Bioko Norte • Malabo-Rebola, Estrada km 4-5, plantaçoes de cacau; [3°44’17”N, 8°49’01”E]; 2 May 1988; Carvalho 3416; MA [MA-684403]. – Centro Sur • Niefang, explotación forestal de Matroguisa; 1°57’N, 10°23’E; 4 Apr. 2000; Pérez Viso 2289; MA [MA-844000].

GABON – Estuaire • Ca 6 km NE of Malibé; 0°35’N, 9°26’E; 20 Dec. 1986; Reitsma 2740; MA [MA-454585], MO [MO-4496692], WAG [WAG.1339019] image. – Ngounié • Bongolo, near protestant hospital; 2°14.2’N, 11°27.7’E; 130 m; 11 Nov. 1994; Wieringa 3137; LBV, MO [MO-4496693], WAG [WAG.1339020]. – Ogooué-Ivindo • Makokou, IRET station; 0°30.7’N, 12°48.1’E; 500 m; 22 Jan. 2004; Wilks 3776; LBV, MA, WAG [WAG.1339018].

Note

According to Prain (1913), this species should not be considered native in Africa.

Tragia zenkeri Pax (Pax 1897: 528)

Fig. 6B

Type

CAMEROON – Centre Region • Yaoundé; Dec. 1893; Zenker & Staudt 88; lectotype (designated here): K [K000425698] image; isolectotype: BM [BM000911173] image.

Description

Twining or scrambling perennial herb or shrub of unknown height; young and mature branches pubescent with stinging hairs up to 0.8 mm long. Stipules triangular-lanceolate, ca 4.3 × 1.2 mm, acute, pubescent with stinging hairs up to 0.8 mm long. Petioles 0.5–2.5 cm long, pubescent with stinging hair up to 0.8 mm long; distal and proximal pulvinate. Leaf blade elliptic, 4.2–8.4 × 2.3–3.8 cm, cordate at base, acuminate at apex, with acumen up to 0.8 cm, sinuate, with few tufted hairs at the teeth apex, upper surface pubescent with stinging hairs up to 0.8 mm, densely on veins, lower surface pubescent with stinging hairs up to 0.5 mm long, densely on veins; basal veins 7, secondary veins 4–5 pairs. Inflorescences bisexual, up to 2 cm; peduncle up to 1.5 cm, densely pubescent with slightly curved hairs up to 0.5–0.8 mm. Male segment up to 0.4 cm long; bracts rounded, ca 1.3 × 1.3 mm, pubescent with stinging hairs up to 0.3 mm long; without bracteoles. Female segment with 1–2 flowers; bracts distally regularly 3–4-dentate until 1/3 of the length, 1.5 × 2 mm, densely pubescent, with hairs, ciliate; bracteoles oblong, 1.5 × 0.5 mm, densely pubescent, with minute hairs, ciliate. Male flower pedicel ca 1.5 mm long, pubescent with minute hairs; buds ca 1 mm in diameter; calyx lobes subrounded, 1 mm long, sparsely hairy with minute hairs; stamens 3; filaments up to 0.5 mm long; anthers 0.7 × 0.5 mm. Female flower sessile; calyx lobes 6, obovate, entire, with 1–3 subulate teeth on each side, 2.1 × 1.1 mm, densely pubescent, with hairs, ciliate; ovary 0.8 × 1.1 mm, densely hispid; styles 0.7–1 mm, connate at base, densely hairy, mainly at base. Fruits sessile, (2–)2.5 × 4.2 mm, densely hispid, hairs up to 0.3 mm; calyx lobes up to 4 mm long, lobulate, laminula oblanceolate, 1.5(–2) × 1(–1.5) mm, with 1–3 teeth, slightly hardened in the central part, densely pubescent, with hairs, ciliate; columella 2 mm long. Seeds 3.5 mm in diameter, dark brown with yellowish patches.

Distribution

Cameroon (Pax 1897; Prain 1913) (Fig. 6B), Equatorial Guinea (Fig. 6B), Gabon (Prain 1913) (Fig. 6B), and possibly present in other Central African countries.

Habitat and ecology

It grows in inselbergs and other rocky areas, forest edges, and galleries at 100–758 m elevation.

Additional material examined

CAMEROON – Centre Region • Mefou Proposed National Park, Ndnan 1, eastern part of parc, track 2, through abandoned village NE of Ndangan 1 to river; 3°37’19”N, 11°36’3”E; 710 m; 19 Mar. 2004; Cheek 11865; BR [BR0000016245891] image, K [K000678394] image • Nkolbisson, 7 km W of Yaoundé; [3°52’14”N, 11°27’16”E]; 700 m; 3 Mar. 1965; Leeuwenberg 5005; BR [BR0000016249097] image. – North-West Region • Nwa subdivision, Lus; [6°40’59.988”N, 10°58’0.012”E]; 650 m; 6 May 1980; Baeke 6; BR [BR0000016248601] image • Piste Baji-Essu, 20 km NNE, Essu, village situé à 20 km au N de Wum; [6°33’59”N, 10°05’12”E]; 500 m; 14 Jul. 1975; Letouzey 14037; BR [BR0000016244979] image, P [P00346742] image. – Unknown region • s.loc.; s.d..; Bagshawe 727; K [K000425699] image.

EQUATORIAL GUINEA – Bioko Sur • Malabo-Luba-Riaba, estrada kms 62–63; [3°24’06”N, 8°44’20”E]; 30 Sep. 1989; Carvalho 4121; MA [MA-845064] • Gran Caldeira de Luba; [3°21’12”N, 8°30’47”E]; 26 Feb. 1990; Carvalho 4261; MA [MA-874885] • Entre el cruce de Moca y Riaba, km 1–2; 750 m; [3°25’11”N, 8°38’56”E]; 13 Feb. 1989; Fernández Casas 11576; MA [MA-845245] • Servicio Agronómico de Musola; [3°26’16”N, 8°36’46”E]; 16 Jan. 1947; Guinea 1426; MA [MA-204013]• Musola S. Agromé site; [3°26’16”N, 8°36’46”E]; 3 Jan. 1951; Guinea 1426bis; MA [MA-02-00294522].

GABON – Nyanga • Moukalaba, Réserve des Monts Doudou, Sud-Ouest de la Brigade de Moukalaba, village Mourindi; 2°34’S, 10°44’E; 100 m; 22 Mar. 2000; Sosef 926; LBV, WAG [WAG.1339085]. – Ogooué-Lolo • Mont Mbigou, surplombe l’ancien village de Komi; 0°58.9’S, 11°49.9’E; 505 m; 30 Apr. 2002; Parmentier 2655; BRLU. – Woleu-Ntem • Oyem, Inselberg Ossapanda; 1°38.82’N, 11°37.79’E; 758 m; 13 Jan. 2003; Ngok Banak 1421; BRLU, LBV, WAG [WAG.1339087] • Minkébé National Park; 1°23.25’N, 12°34.00’E; 635 m; 2 May 2003; Ngok Banak 1555; BRLU, LBV, MO [MO-4496663], P n.v., WAG [WAG.1339086] • Mont Miwa, inselberg à 3 km du village de Kumassi, à 35 km d’Oyem vers Bitam; 1°50’N, 11°38’E; 720 m; 15 Apr. 2002; Parmentier 2337bis; BRLU.

Notes

Tragia zenkeri was previously treated as a synonym of T. tenuifolia Benth. We reinstate this species here after studying the type material, and identify it as a new record for Gabon.

We have selected as the lectotype of Tragia zenkeri the specimen Zenker & Staudt 88 because it is the best-preserved preparation and includes all the morphological details for proper identification. A duplicate of this gathering was probably lost because of the bombing raid that affected the Berlin Herbarium.

After the study of material from the continent and the islands, we can confirm that T. tenuifolia is endemic to São Tomé, growing in xeric coastal formations. The copious material identified as T. tenuifolia from mainland Africa belongs to various morphologically similar species (T. laminularis, T. mildbraediana, or T. spathulata). Some of the Gabonese collections cited by Sosef et al. (2006) under Tragia sp. (Ngok Banak 1421, 1555; Sosef 926) belong to T. zenkeri.

Tragia zenkeri occurs in West-central Africa, where T. mildbraediana and T. sericea are also present (see Diagnosis of T. sericea and Notes with T. mildbraediana).

Acknowledgements

We kindly thank the curators and staff of the herbaria BM, BR, BRLU, COI, G, K, LBV, LISC, LISU, MA, MO, P, and WAG for their help while working at their institutions, for sending specimens on loan, and for taking images when needed. The author Iris Montero-Muñoz received a Juan de la Cierva – Formación-2021, grant ref. FJC2021-046607-I, funded by MCIN/AEI/ 10.13039/501100011033 and European Union NextGenerationEU/PRTR, and the author Patricia Barberá is funded by the Atracción de Talento Investigador César Nombela with ref. 2023-T1/ECO-29341 (Comunidad de Madrid). This paper partly draws on the result of numerous field trips conducted in Gabon by the Missouri Botanical Garden (MBG) and the Herbier National du Gabon, undertaken under the Memorandum of Understanding between the MBG and the Centre National de la Recherche Scientifique et Technologique (CENAREST). We thank the director and vice-director of IPHAMETRA (Institut de Pharmacopée et de Médecine Traditionelle), Sophie Aboughe Angone and Nestor Engone Obiang, for allowing our research. Part of the fieldwork was supported technically by the Agence Nationale des Parcs Nationaux (ANPN) and funded by the Prince Albert II de Monaco Foundation and the Communauté française de Belgique. CENAREST also provided the necessary research permits for the field work (permit AR0045/19/MESRSTT/ CENAREST/CG/CST/CSAR). We are also grateful to Jean Philippe Biteau (Jardi-Gab) and to the Wildlife Conservation Society (WCS) Gabon for assistance provided during each of the trips to Gabon. P gave access to the collections in the framework of the RECOLNAT national Research Infrastructure (ANR11-INBS-0004). We also express our gratitude to Alejandro Quintanar for his comments and suggestions, and Marc Sosef for his help in different processes of the manuscript, which significantly improved its quality. Finally, we thank Hilde Orye for her excellent illustration and Olivier Lachenaud for all the support and great photos of one of the new species.

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